LTX Units and Line Heaters
LTX Coil Sizing – Coil Lengths
With the known temperatures on each end of the coil, the heat duty for each coil can be calculated from the heat transfer theory. Since the bath is at a constant temperature, LMTD can be calculated as:
The overall film coefficient, U, for the coil can be calculated or read from the charts and tables in [...]
16Sep2009 | admin | Comments Off | ContinuedLTX Coil Sizing – Choose Wall Thickness
Before choosing a wall thickness it is necessary to choose a pressure rating for the coil. Typically, the high-pressure coil (L1) is rated for the shut-in pressure of the well, and the low-pressure coil (L2) is rated for the maximum working pressure of the downstream equipment. There are many exceptions to this rule and reasons [...]
16Sep2009 | admin | Comments Off | ContinuedLTX Coil Sizing – Choose Coil Diameter
Erosional flow criteria will almost always govern in choosing the diameter. Sometimes it is necessary to
check for pressure drop in the coil. Typically, pressure drop will not be important since the whole purpose of the line heater is to allow a large pressure drop that must be taken. The allowable erosional velocity is given by:
The [...]
16Sep2009 | admin | Comments Off | ContinuedLTX Coil Sizing – Choose Temperatures
In order to choose the coil length and diameter, a temperature must first be chosen upstream of the choke; the higher Th the longer the coil L] and the shorter the coil L2. In Heat Transfer Theory we showed that the greater the LMTD between the gas and the bath temperature, the greater the heat [...]
16Sep2009 | admin | Comments Off | ContinuedFire Tube Size
The area of the fire tube is normally calculated based on a heat flux rate of 10,000 Btu/hr-ft2. The fire-tube length can be determined from:
where L = fire tube length, ft
q = total heat duty, Btu/hr
d = fire tube diameter, in.
A burner must be chosen from the standard sizes in Table 2-12, For example, if [...]
LTX Units Heat Duty
To calculate the heat duty it must be remembered that the pressure drop through the choke is instantaneous. That is, no heat is absorbed or lost, but there is a temperature change. This is an adiabatic expansion of the gas with no change in enthalpy. Flow through the coils is a constant
pressure process, except for [...]
Line Heaters
As shown in Figure 5-2, the wellstream enters the first coil at its flowing tubing temperature and pressure. Alternatively, it could be choked at the wellhead to a lower pressure, as long as its temperature remains above hydrate temperature.
There is typically a high-pressure coil of length L1, which heats the wellstream to temperature, T1. The [...]