DE8511057U1 - Pressure holding head - Google Patents

Description

The invention is used to:

Keeping the pressure constant in fluid-filled rooms Sealing pressure constant with double mechanical seals as well as tandem mechanical seals occurring in the industry and fully automatic balancing car Leakage quantity

Purpose:

Shaft seals in special designs (double or tandem) are used for shaft seals of centrifugal pumps, agitators, compressors and other rotating machines in industry that convey environmentally hazardous, toxic, explosive, etc. liquids or seal gases. These have so-called barrier fluid spaces, which must have a certain constant overpressure compared to the product to be sealed.

As a result of this overpressure, the, for example, difficult to seal, environmentally hazardous or explosive products cannot enter the atmosphere and contaminate or endanger the atmosphere.

The system on which the invention is based maintains this overpressure with high accuracy and compensates for the leakage quantities of the pure barrier product that occur.

State of the art:

Maintaining constant pressure in rooms, such as shaft sealing rooms, has so far been carried out as follows:

1. Using so-called thermosiphon containers, whose use has the following disadvantages:

a) Direct gas / barrier product contact, thus indiffusion of the gas into the sealing liquid and as a result, in some cases a significant reduction in the service life of the shaft seals.

b) Very small work volume and thus high maintenance costs, which has already led to many failures.

c) The level indicator is under system pressure, which means that costs are intense.

d) Standing contact is under system pressure, which means that it is cost-intensive.

e) above a ρ χ v-ratio of 200 these are subject The strict regulations of the Pressure Vessel Ordinance.

f) The operator who "uses" this thermosiphon container, has an additional effort for the prescribed repeat tests due to the pressure vessel regulation,

2. Barrier pressure systems -nit open .: barrier circuit with unpressurized Storage tank, 1 or 2 positive displacement or centrifugal pumps, Pressure control etc.

This system requires the power supply for one or two circulation pumps (in average, the cost of running it is DM 4,000 to DM 6,000 per power supply line).

This system constantly devours electricity costs (1 kVJ costs between DM 1,000 and DM 1,800 per kW / year at 8, OOO operating hours per year).

This system generates the barrier pressure and relaxes it back to zero after the sealing chambers. As it is If a circulatory system is involved, almost the entire one changes!

Energy (almost the engine output) is converted into heat, which then has to be cooled down again accordingly. Compared to other systems, this is a form of energy destruction that costs industry a lot of money.

In certain cases it is necessary to have already low Detect leakage quantities of the barrier product and give an alarm if they penetrate the product that is being sealed. With this system, detection is less Leakage quantities from a sealing chamber (if several sealing chambers are connected to the same system) not possible.

The above two systems are the most widely used in the market. Damage analyzes show that 50 - 70% of the cause of failure in rotating machines is repeatedly caused by shaft seals. The shaft seal is therefore the part that fails most frequently. The relatively short service lives of double and tandem mechanical seals show that the barrier pressure maintenance systems currently on the market do their job for

Long service life of the connected shaft seals. Operational reliability of the connected shaft seals Maintenance arir.ut of the connected mechanical seals low energy costs

not yet meet. Achievable benefits:

The advantages that can be achieved with the invention are as follows:

- 4th

a) The preload pressure pl existing in the accumulator is not in connection with that of the pressure maintenance

"Liquid pressure p2. This means that there is no diffusion of gas into the liquid, which significantly increases the service life of the mechanical seals.

b) Depending on the air or inert gas pressure pl, the pressure p2 is kept constant at all times by a pneumatic pressure switch (item 1) connected to this space and a pneumatically driven piston pump. This increases the operational reliability compared to other systems.

c) Gas system enables much better monitoring of connected consumers than those on the market.

d) When using this system, no power line is required for the drive energy. This reduces the Investment costs are considerable and so are the energy costs. The energy costs are lower than those on the market existing systems.

e) Economic efficiency, operational safety, increased service life the connected machines, low maintenance etc. are advantages of this invention, making them the ones on the market Systems is superior.

ff When using the invention, the environmental pollution is compared to the systems on the market as Primary and secondary effect reduced. (Every failure of a Shaft seals that are toxic or environmentally hazardous Seals products, contributes to air and wastewater pollution.)

- 5th

Description for sketch II

Pos. 1) Pneumatic pressure switch

Pos. 2) Diaphragm accumulator

Pos. 3) Filling connection for preload pressure

Pos. 4) pressure holding head

When the liquid pressure p2 drops below the diaphragm the pressure switch (pos. i) switches on air ύΰ «ϊ inert gas a pneumatic piston pump. This pneumatic piston pump increases the fluid pressure p2 back to the set value. p2 and pl are then the same pressure.

Description of sketch 2:

Fos. 1) Pneumatic pressure switch

Pos. 2) Diaphragm accumulator

Pos. 3) Filling connection for Ycrspar.naruck

Pos. 4) pressure holding head

Item ^r j) Manometer

Item t) 3 tank level over </ caution

Pos. 7) Pressureless storage container for liquid

Pos. 16) Contact pressure gauge

Item 20) Overflow valve

Item 50) check valve

Item 54 and Item 116) Filter regulator

Pos. 9O) 3/2-way valve

Item 91) filler filter

Item 92) Level indicator

Claims (1)

• ar · * · «■« • w · a · * · _a Protection claims - the pressure holding head (item 4 '; is in direct connection with the preload pressure chamber of the diaphragm accumulator, - the pressure holding head (item 4) is in direct connection with a pneumatic pressure switch (item 1), - A commercially available thread and valve (item 3) are available to build up the preload pressure. to keep the pressure constant in the event of a pressure drop, the unit of pressure holding head and pressure switch (pos. 1 + 4) via the pneumatically driven differential piston pump (Item 8) is used, Ettlingen-Schöllbronn, August 26, 1985