Vacuum deaeration system 10 m3

PAS „Daugavpils siltumtikli“

Daugpilis, Latvia

2021

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Main technical requirements for the system:

1. Vacuum deaerator performance – 10 m³/h
2. Deaerator working range – from 2 m³/h to 10 m³/h
3. Initial concentration of dissolved oxygen in water – 2700 µg/l
4. Initial condensate parameters: flow 2.5-3 m³/h, pH 4, temperature 43-48°С
5. The concentration of oxygen dissolved in water after the deaerator is no more than 45 µg/l
6. For water heating before the deaerator is used water with a temperature of 80 to 95°С (water is supplied from the recirculation system of the gas boiler)
7. Use the existing atmospheric deaerator storage tank
8. Ensure operation of the deaerator with zero discharge of cooling water from vacuum pumps into the sewer

Results:

When water temperature before the deaerator is 70-75°С, dissolved oxygen in the water after the deaerator is 25-45 µg/l; pH=7-7.5 (without adding NaOH to the condensate).

The customer wanted the pH of the make-up water to be at least 8.5, so we switched on NaOH deaeration and neutralized the condensate before the deaerator to pH=6. Since the condensing economizer (designed and supplied by UAB "Gandras energoefektas" UAB) not only increases the overall efficiency of the boiler to 105-107%, but also reduces NOx emissions from 100 to 47 mg/Nm³, we assumed that nitrogen, which the vacuum deaerator was unable to neutralizme, was also involved in addition to dissolved carbonic acid.

Conclusions:

1. Prior to the installation of the vacuum deaerator, the customer used a chemical reagent - an oxygen suppressor, which cost four times more expensive than the operation of the vacuum deaerator.
2. Before installing the vacuum deaerator, the customer used twice as much NaOH to neutralize the condensate from pH=4 to pH=8.5 (after installing the deaerator, it is necessary to neutralize from pH=4 to pH=6).
3. During the implementation of this project, it was necessary to change the pipeline before the make-up pumps, because the atmospheric deaerator has excess pressure, and the vacuum one has a vacuum of up to 0.3 bar(a).

The scheme proposed by UAB "Gandras energoefektas" allowed to fulfill all the customer's technical requirements.