EP1780460B1 - Apparatus to increase pressure - Google Patents

Abstract

Device has a metering container (7) and evaporator (9,10) attached to tank system whereby tank system is connected to metering container over valve (1) and inlet pipe (6). Tank system is connected with evaporator over connecting pipe (8) consisting of valve (2) whereby evaporator is branched one side over return piping (11) with valve (4). Supply piping (6) is connected to metering container and on the other side branched to bleed line (13) with valve (3).

Description

The invention relates to a device for increasing the gas pressure of cryogenic, liquefied gases from tank systems. Such a system is from the document DE-A-196 16 811 known.

Usually, technical gases, e.g. Stored oxygen, nitrogen, carbon dioxide, etc. in cryogenic, liquid state in vacuum-insulated tank facilities. If required, the liquid gases are brought to near ambient temperature via evaporators and used in gaseous state for subsequent processes. For most processes, the operating pressures of the existing tank systems are sufficient. But if gas at pressures above the maximum operating pressure of the tank systems, which is approximately 36 bar for standard tank systems and about 36 bar for high-pressure tank systems, required, special tank systems or pressure boosting systems would be used. Conventional pressure booster systems work with pumps for liquid gases or compressors for already gaseous gases.

For some gases, the use of pumps or compressors to increase pressure can be problematic. For example, the pressure increase of oxygen by means of mechanical compressors can lead to the danger of explosion due to friction.

A new field of application for the gas pressure increase of industrial gases is the treatment of sewage sludge from sewage treatment plants. In order to improve the drainability of sewage sludge, various methods for sludge disintegration are used. The cell walls of the microorganisms contained in the sewage sludge are destroyed, whereby a thickening of the sewage sludge is substantially facilitated. In the not pre-published DE 102 00 4042 773.9 describes a process for sewage sludge disintegration, in which the sewage sludge in a pressure reactor is exposed to a gas under high pressure (eg 10 to 200 bar above atmospheric pressure). By suddenly relaxing the gas-saturated microorganisms, the cell walls rupture, releasing the cell interior. The gases used are technical gases such as oxygen, nitrogen or carbon dioxide. These are available in standard fueling systems whose operating pressure is not always sufficient for this process. Therefore, additional pressure booster systems must be provided. However, conventional pressure booster systems are problematic because the required discontinuous operation, a cold running of the pump is difficult. In addition, such pressure booster systems are associated with high acquisition costs. The booster systems equipped with pumps or compressors also have sensitive units that require high maintenance and operating costs.

The present invention has for its object to provide a gas pressure booster system for supplying gases from tanks for cryogenic liquefied gases available, which largely manages without mechanical compressors or pumps.

This object is achieved in that the tank system is connected via a valve having a feed line with a metering, which in turn is connected via a valve having a connecting line with an evaporator in connection, wherein the evaporator on the one hand via a valve having a return line from the a bleed line having a valve (5) branches off, is connected to the supply line to the metering container and on the other hand leads away a removal line having a valve from the evaporator.

The proposed gas pressure booster thus has neither pumps nor compressors and comes with conventional containers and evaporators. Through the described interconnection of metering and evaporator, the gas taken from a standard liquefied gas tank can be increased to the desired pressure.

In order to enable a continuous or discontinuous supply of a consumer with the gas under increased pressure, the removal line of the evaporator is preferably in communication with at least one gas storage. The gas storage can be designed as a gas container or as a cylinder bundle.

By changing the volume ratio of dosing and gas storage different pressure ranges can be adjusted. Preferably, the volume of the dosing and the volume of the gas storage in the ratio 1:10 to 1: 200. For example, the dosing can have a volume of 4 to 10 liters, while the gas storage consists of several gas storage containers, in particular a gas cylinder bundle with 5 to 12 gas cylinders.

The metering container is preferably vacuum-insulated.

Conveniently, an air-heated evaporator is used as the evaporator, in which the evaporation takes place by ambient air. When using water bath evaporators or by heating with electrical energy, the performance of the pressure booster can be increased even more.

The invention offers a whole series of advantages:

By eliminating pumps and compressors maintenance and operating costs compared to conventional gas pressure booster systems are significantly reduced. In addition, no additional power requirement for drives is required. The use of conventional containers and evaporators allows low investment costs. Since the increase in pressure occurs solely by the evaporation of gas, the problems that occur in mechanical gas pressure booster systems, in principle, can not occur. Even a continuous or discontinuous operation is easily possible. Through the use of a simple dosing container, of standard electrically or pneumatically operated shut-off valves, standard or slightly modified finned tube evaporators or Rippenrohbehältern a total of a very inexpensive gas pressure booster system is provided. In this case, a preparation of the system in different sizes is readily possible. Depending on the volume ratio of metering and gas storage any desired extraction pressure range can be determined. Finally, for cold running a relatively small volume or a small amount of material of the dosing is required.

The invention is suitable for all processes in which gases from standard liquefied gas tank facilities are required at higher pressures than the operating pressures of the tank installations. A particularly interesting application is the disintegration of sewage sludge by the application of gases under high pressures.

In the following, the invention will be explained in more detail with reference to an embodiment schematically illustrated in the figure:

The figure shows a pressure booster for increasing the gas pressure of oxygen from a liquid oxygen tank system. This pressure booster system is intended for the gas supply of a reactor for the disintegration of sewage sludge. The reactor for the disintegration of sewage sludge is not shown in the figure.

From a liquid gas tank for oxygen, not shown in the figure, a previously relaxed metering 7 is filled via line 6 by pressure with liquid oxygen. The metering container 7 is connected via a line 8 with a consisting of a cold part 9 and a warm part 10 evaporator. A return line 11 leads back to the dosing 7. To the return line 11, a vent line 12 is connected to a muffler. The warm part 10 of the evaporator is connected via a line 13 with an existing gas cylinder bundle 14 gas storage in combination. A provided with a pressure reducer 16 gas discharge line 15 finally leads to the reactor, not shown, for the disintegration of sewage sludge.

The operation of the gas pressure booster plant is carried out as follows:

In the initial situation, the valves 1 and 5 are closed. The gas is removed via valve 3. When the valve 3 is open, the gas pressure in the oxygen cylinder bundle 14 drops. When the pressure falls below a predetermined minimum pressure of, for example, 48 bar, the valves 2 and 4 are closed. To release the dosing container 7 to ambient pressure, the valve 5 is opened and closed again after about 10 seconds. Subsequently, the valve 1 is opened and the dosing 7 filled with liquid oxygen from the connected tank system, which is operated for example at a tank pressure of about 18 bar. After filling the dosing tank 7, which is achieved, for example, after 30 seconds, the valve 1 is closed again. Then the valve 4 is opened and the pressure in the dosing tank 7 increases until pressure equalization. Valve 2 is opened so that the liquid oxygen flows into the cold part 9 of the evaporator. In this case, a pressure equalization takes place via valve 4. By evaporation of the liquid oxygen increases Pressure in the evaporator 9, 10 and in the oxygen cylinder bundle 14 according to the volume ratio. When falling below the predetermined minimum pressure of eg 48 bar, the steps described above are repeated.

By venting the dosing container 7 with a volume of e.g. 6 liters at 48 bar creates a gas loss (6 liters x 48 bar) of 288 liters. In percentage terms, the theoretical losses (288 liters / 5,118 liters) are 5.63%. In practice, these losses are likely to be 6 to 8%. However, these losses can be minimized by the following use of the exhaust gas at a pressure of about 2 to 3 bar:

The gas may e.g. used to drive pneumatic valves instead of compressed air. When using the gas pressure booster for the disintegration of sewage sludge, the gas can also be used for other processes with lower gas pressure. For example, oxygen can be used for the additional fumigation of activated sludge plants in sewage treatment plants. A partial relaxation in the tank to build up pressure is possible.

By simple adaptation of the volume ratios of dosing 7, evaporator 9, 10 and oxygen cylinder bundle 14, the system for each pressure and each amount of gas is applicable.

• Gas für die Desintegration: Sauerstoff
• Erforderlicher Gasdruck im Desintegrationsreaktor: maximal 45 bar
• Erforderlicher Gasdurchsatz (Gasdosierung 60 Nm³/h): 5 Nm³/5 Minuten
• Gasbedarf: 3 bis 4 mal pro Stunde
• Betriebszeit: 8 bis 12 Stunden pro Tage
• Gasspeicher: Sauerstoff-Flaschenbündel

• Volumen des Dosierbehälters: 6 Liter
• Volumen des Verdampfers (kalter Teil): 2 bis 10 Liter
• Volumen des Flaschenbündels: 600 Liter
• Maximaler Systemdruck: 48 bar

• 1 Liter Sauerstoff (flüssig) entspricht 853 Liter Sauerstoff (gasförmig) bzw. 0,85 Kubikmeter bei 1 bar.
• 6 Liter Sauerstoff (flüssig) entsprechen 5.118 Liter (gasförmig) bzw. 5,1 Kubikmeter bei 1 bar.

The following design example relates to the use of the gas pressure booster for the disintegration of sewage sludge. The sewage sludge is filled into a reactor and gassed with oxygen under high pressure. Sudden release of the gas-saturated microorganisms will burst the cell walls, significantly improving the drainability of the sewage sludge. The reactor for the disintegration of sewage sludge must therefore be supplied discontinuously with a high pressure oxygen gas. For this purpose, a gas pressure booster with the following technical data is used:

• Gas for disintegration: oxygen
• Required gas pressure in the disintegration reactor: maximum 45 bar
• Required gas flow rate (gas dosage 60 Nm ³ / h): 5 Nm ^3/5 Minutes
• Gas needs: 3 to 4 times per hour
• Operating time: 8 to 12 hours per day
• Gas storage: oxygen cylinder bundles

• Volume of the dosing tank: 6 liters
• Volume of the evaporator (cold part): 2 to 10 liters
• Volume of the bottle bundle: 600 liters
• Maximum system pressure: 48 bar

• 1 liter of oxygen (liquid) corresponds to 853 liters of oxygen (gaseous) or 0.85 cubic meters at 1 bar.
• 6 liters of oxygen (liquid) correspond to 5,118 liters (gaseous) and 5.1 cubic meters at 1 bar.

According to the relationship px V = constant [200 (bar) x 0.6 (m ³ ) = 120 (m ³ )], the oxygen volume of the gas storage at 48 bar (48 bar x 0.6 m ³ ) is 28.8 cubic meters.

$$33,9{\mathrm{m}}^3\times (200\mathrm{bar}/120{\mathrm{m}}^3)=56,5\mathrm{bar}$$

At a feed of 6 liters (= 5.1 m ³ ) of liquid oxygen, the pressure rises (without simultaneous gas sampling) on: $$28.\mathrm{<figure-callout\; id="3"\; label="8th\; m"\; filenames="imgf0001.png"\; state="\{\{state\}\}">8th\; </figure-callout>}{\mathrm{m}}^{}{\mathrm{}}^3+5.1{\mathrm{<figure-callout\; id="3"\; label="m"\; filenames="imgf0001.png"\; state="\{\{state\}\}">m</figure-callout>}}^3=33.9{\mathrm{<figure-callout\; id="3"\; label="m"\; filenames="imgf0001.png"\; state="\{\{state\}\}">m</figure-callout>}}^3$$

$$33.9{\mathrm{<figure-callout\; id="3"\; label="m"\; filenames="imgf0001.png"\; state="\{\{state\}\}">m</figure-callout>}}^3\times (200\mathrm{bar}/120{\mathrm{m}}^3)=56.5\mathrm{bar}$$

Claims (7)

1. Device for the increase of gas pressure of low-temperature liquefied gases from tank installations, characterized in that the tank installation can be connected, via a delivery line (6) having a valve (1), to a metering container (7) which is itself connected, via a connecting line (8) having a valve (2), to an evaporator (9, 10), on the one hand the evaporator (9, 10) being connected to the delivery line (6) to the metering container (7) via a return line (11), which has a valve (4) and from which a venting line (12) having a valve (5) branches off, and, on the other hand, an extraction line (13), which has a valve (3), leading away from the evaporator.
2. Device according to Claim 1, characterized in that the extraction line (13) is connected to at least one gas accumulator (14).
3. Device according to Claim 2, characterized in that the volume of the metering container (7) and the volume of the gas accumulator (14) are in a ratio of 1:10 to 1:200.
4. Device according to one of Claims 1 to 3, characterized in that the evaporator (9, 10) is designed as an air-heated evaporator.
5. Device according to one of Claims 1 to 3, characterized in that the evaporator (9, 10) is designed as a water-bath evaporator.
6. Device according to one of Claims 2 to 5, characterized in that the gas accumulator (14) is designed as a gas holder or bottle bundle.
7. Device according to one of Claims 1 to 6, characterized in that the metering container (7) is vacuum-insulated.

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