Installation of Drum Level Control

Installation of drum level control should be carried out properly. Drum level control was previously known that the level of boiler water in a steam drum differs significantly due to circulation of water and changes in load of steam boiler.

These conditions merge to generate it quite hard to control and observe precision level of boiler water. What exactly is needed is a quiet surface of water is which can be representative of exact level of boiler water.
Installation of drum level control can be equipped with probe type or float type and it can be performed through two methods as follow:

1. Inside protection tubes.
2. Outside drum level indicator.

    - Inside protection tubes (one on one installed level settings)

Inside protection tubes occasionally known as one on one installed level settings, and so they need protection tubes for being mounted inside steam drum shell as demonstrated in Figure 1. The 1st and 2nd low level equipment should be installed in independent protection tubes, therefore that they're fully separate of one another.

Figure 1: Arrangement of Inside Installation of Drum Level Control
(Source: book-The Boiler House-Spirax Sarco)

The protection tubes independently may not be common products, and will probably be exclusively fabricated per specific steam boiler. On the other hand, for the reason that protection tubes design provide a real significant impact on the effective function of drum level control, the examples below give some instruction for installation of drum level control:

·    Length:

Inside protection tubes must move as far down among the tubes seeing that actually doable.

·    Diameter:
To make sure constant circumstances and give adequate clearance pertaining to probe centering, bore protection tube is made with size 80 mm. In which 2 probes (such as, level control probe additionally self-supervising probe for low level) can be mounted in an individual bore protection tube is needed with size 100 mm.

-     Outside drum level indicator

Drum level control is installed on the outside of drum in a steam boiler system. Drum level control is commonly, although not often, installed by using float settings. Several common placements are demonstrated in Figure 2.

Figure 1: Arrangement of Outside Installation of Drum Level Control
(Source: book-The Boiler House-Spirax Sarco)

Two outside drum level indicator are required due to:

·     One outside drum level indicator for detects low level.

·     Another outside drum level indicator for detects low level and high level of boiler water in steam drum.

This particular means that the 2 low sensors will be in separate drum level indicator. The outside drum level indicator can be installed by using “sequencing valve' along with isolating valve.