Patent ID: 11857917
Assignee: ATLAS COPCO AIRPOWER, NAAMLOZE VENNOOTSCHAP
Field: Chemical engineering (Chemistry)
Classification: CPC B | IPC B

Claim 0:
1. A method for drying compressed gas by means of a drying device with an inlet for the compressed gas to be dried and an outlet for the dried compressed gas, wherein the drying device comprises at least two vessels filled with a regenerable desiccant and an adjustable valve system comprising a first valve block and a second valve block that connects the inlet and the outlet to the vessels, wherein the method comprises
inputting compressed gas to the at least two vessels via the adjustable valve system;
regulating the adjustable valve system such that at least one vessel dries the compressed gas while the other vessel is regenerated and cooled successively,
wherein by regulation of the valve system the vessels each in turn dry the compressed gas, and
wherein the step of regulating the adjustable valve system comprises steps of:
(i) calculating the time period (tads) during which a vessel dries the compressed gas, without input from a dew point sensor, on the basis of a formula:

tads=A*B; 

where:
tads=the period of time during which a vessel dries compressed gas;
A=a predetermined adsorption time;
B=a product of one or more of the following factors:
CΔP=a correction factor for correcting the predetermined absorption time based on a comparison between the average pressure drop (ΔPgem) over the drying device and a reference pressure drop (ΔPref) over the drying device;
CP=a correction factor for correcting the predetermined absorption time based on a comparison between the average inlet pressure (Pgem) and a reference inlet pressure (Pref);
CT=a correction factor for correcting the predetermined absorption time based on a comparison between the average inlet temperature (Tgem) and a reference inlet temperature (Tref);
C=a fixed correction factor;

where the reference pressure drop (ΔPref), reference inlet pressure (Pref) and reference inlet temperature (Tref) are the values measured or determined in the drying device when operating under reference conditions, where B comprises at least the factor CP;
(ii) controlling the first and second valve blocks to input the compressed gas to a first of the at least two vessels, for the calculated time period, and thereby dry the compressed gas in the first of the at least two vessels;
(iii) controlling the first and second valve blocks to prevent input of the compressed gas to a second of the at least two vessels during the calculated time period, and allow the dessicant in the second of the at least two vessels to regenerate.