Vacuum regulation

Since (c) is larger than (a) in the previous step, too thick a cake will be formed and it will not wash or dry adequately unless the effective submergence is artificially restricted to yield the design cake thickness. This may be accomplished by proper bridge-block adjustment or by vacuum regulation within the form zone of the filter valve. 

What if the vacuum regulator check unit fails ... 

What if there is liquid chlorine/sulfur dioxide carryover to the vacuum regulating valve downstream of the evaporator ... 

Inspect the plant and remove any deposits, check position of valves and settings of temperature and vacuum regulators... 

The vacuum regulation valve produces a constant vacuum after the V-notch orifice. An incorporated vacuum breaker prevents excessive vacuum. At the injector the chlorine gas is dissolved in the caustic dilution water and thus mixed thoroughly. The resultant solution is discharged in the manifold where dilution water and caustic solution are mixed. 

Chemical feeders for gases are remarkably similar regardless of the chemical. A chlorinator can feed sulfur dioxide, anhydrous ammonia, and carbon dioxide with only minor adjustments. Carbon dioxide, for example, is contained at a higher pressure. This condition requires installing a pressure-reducing valve between the supply and the vacuum regulating valve. For ammonia feed, the injector... 

Most continuous pressure filters available (ca 1993) have their roots in vacuum filtration technology. A rotary dmm or rotary disk vacuum filter can be adapted to pressure by enclosing it in a pressure cover however, the disadvantages of this measure are evident. The enclosure is a pressure vessel which is heavy and expensive, the progress of filtration cannot be watched, and the removal of the cake from the vessel is difficult. Other complications of this method are caused by the necessity of arranging for two or more differential pressures between the inside and outside of the filter, which requires a troublesome system of pressure regulating valves. 

The BHS-Fest Filter. A different approach to the use of a dmm for pressure filtration is made in the BHS-Fest filter (Fig. 24). This permits a separate treatment of each filter section, in which the pressure may vary from vacuum to a positive pressure pressure regulation is much less difficult than in the conventional enclosed dmm-type pressure filter. 

Capacity Control The simplest way to regulate the capacity of most steam vacuum refrigeration systems is to furnish several primary boosters in parallel and operate only those required to handle the heat load. It is not uncommon to have as many as four main boosters on larger units for capacity variation. A simple automatic on-off type of control may be used for this purpose. By sensing the chilled-water temperature leaving the flash tank, a controller can turn steam on and off to each ejector as required. 

Hand-crimp the hose in back of the test leaf, and then turn on the vacuum pump and regulate the bypass valve on the pump to give the desired vacuum level in the receiver. 

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