Download
1 / 14
150 likes | 321 Views
Offtake Arrangements Document. 25 th February 2011. Revisions to Offtake Profile Notices. 4 hours notice is required if the flow rate change at an offtake is not less than 50% of the Maximum Flat Offtake Rate (MFOR), 1/24th of the Maximum Daily Quantity
E N D
Offtake Arrangements Document 25th February 2011
Revisions to Offtake Profile Notices • 4 hours notice is required if the flow rate change at an offtake is not less than 50% of the Maximum Flat Offtake Rate (MFOR), 1/24th of the Maximum Daily Quantity • 2 hours notice is required if the flow rate change at an offtake is less than 50% but not less than 25% of the MFOR • 1 hour notice is required if the flow rate change at an offtake is less than 25% of the MFOR • 1 hour notice is required when there is a decrease in rate of offtake
Revisions to Offtake Profile Notices • The minimum notice required if there is a change in the aggregate rate of offtake to an LDZ is 2 hours • The aggregate flow rate change shall not exceed 5% • A revised Offtake Profile Notice (OPN) must not be submitted more frequently that once in each hour • A revised OPN must not be submitted later that 04:00 on the gas flow day
Low Demand Days • If at the 13:00 preceding day demand forecast the demand for an LDZ is less than 50% of the 1 in 20 peak day, NTS can declare a low demand day prior to 17:00 on the preceding day. If this is declared the DNO is required to flow at a flat profile. A revised OPN can be submitted to reflect changes in the forecast LDZ demand.
Offtake Tolerances • The tolerance for an offtake is 10% of the prevailing offtake rate. The tolerance in aggregate for all offtakes is 3% of the aggregate prevailing offtake rates.
Pressure • The DNO shall submit a pressure request for each offtake when submitting the initial OPN for the day. A revised pressure request can be sent up to but not after 24:00 hours on the day. In agreeing a pressure the NTS will consider the safe and efficient operation of the NTS and the DNO will consider the safe and efficient operation of the LDZ.
TPD – User Offtake Obligations • The maximum permitted rate in respect of an NTS LDZ offtake is a rate calculated as: (Flat Capacity / 24) + (Flexibility Capacity / 4) • NTS will not be obliged to make gas available for offtake in the period between 06:00 and 22:00 hours on any day in a quantity which exceeds (Flexibility Capacity) + (16/24 * Daily Quantity)
Issues • All offtakes, regardless of their mode of operation (volumetric or pressure controlled) and booked MDQ, are treated identically in terms of changes to flow rates. • Offtake tolerances are breached in the first and last hours of the gas day for volumetric offtakes due to gas demand changes. • NTS could declare a low demand day for 6 months of the year in a seasonally normal demand year if they wished to do so. • Pressure requests are required for all offtakes regardless of their criticality to the NTS or to the DNO.
Issues • The NTS can request a lower pressure at an offtake that meets the safe and efficient rule but causes the DNO to operate a different offtake in the same LDZ above the booked MDQ. This can also cause breaches to offtake flow rate and OPN tolerances • Clarification of flow swap rules
