RU2146001C1 - Mobile heat exchanger to heat technological fluid on well - Google Patents

Abstract

FIELD: gas and oil production. SUBSTANCE: invention is related to aids meant to pump technological fluids, specifically, to pump down heated solvent for dewaxing of underground equipment of well. Internal tubes on outside in multiway heat exchanger of "tube in tube" type are equipped with spiral finning. Tube pairs connected in series are placed in the form of S-shaped horizontal tube bundle and are placed into cylindrical enclosure. In upper tube pair external and internal tubes are continued downstream of enclosure and are provided with drain and supply ducts. In lower tube pair internal tube has tangential outlet to internal space of enclosure and external tube is continued downstream of enclosure and is provided with supply duct to feed heated fluid. Rear wall of enclosure is equipped with L-shaped drain branch pipe with side hole in upper part that ensures outlet of heat transfer agent and its level in enclosure. Provision for intensive heat exchange process in apparatus under optimum overall dimensions of heat exchanger makes it possible to use it effectively as mobile facility for heating and simultaneous pumping down of technological fluids based on hydrocarbon solvents in process of thermal chemical treatment of wells. EFFECT: increased functional efficiency of mobile heat exchanger. 3 dwg, 1 tbl

Description

 The alleged invention relates to a means of heating process liquids and oil and gas production, in particular it is used to pump heated solvent during dewaxing of underground well equipment, and can be used in petrochemical and other industries.

 Known shell-and-tube heat exchangers for heating liquids, consisting of inlet and outlet collectors and a tube bundle fixed in tube sheets, which are enclosed in a common casing / 1 /.

 The disadvantage of these heat exchangers is the restriction in use under high pressure conditions, necessary to ensure the continuity of the process of heating and pumping the process fluid into the well. In addition, a complex design of the heat exchanger is required with a significant temperature difference between the heat exchanging media.

 Also known is selected as the closest analogue to a heat exchanger for heating process fluids in the well, containing inlet and outlet channels for a coolant and a heated fluid, series-connected multi-way pipe pairs consisting of external pipes with spiral finning of external surfaces / 2 /.

 The disadvantage of these heat exchangers is the bulky design and high metal consumption per unit of heat transfer surface. A significant area of the outer surface of the outer pipes is not involved in the heat transfer process, but rather is a source of heat loss.

 The purpose of the invention is to increase the efficiency of heat transfer due to the rational use of the coolant.

 This goal is achieved by the fact that in the multi-pass pipe-to-pipe heat exchanger, the inner pipes are provided with spiral fins from the outside. Serially connected pipe pairs are arranged in the form of an S-shaped horizontal tube bundle and are placed in a cylindrical casing. In the upper pipe pair, the outer and inner pipes behind the casing have a continuation, where they are equipped with respectively outlet and inlet channels. In the lower pipe pair, the inner pipe has a tangential exit into the inner cavity of the casing, and the outer pipe has a continuation behind the casing and is equipped with a supply channel for the intake of heated fluid. The casing at the rear wall is equipped with an L-shaped outlet pipe with a side hole in the upper part, providing the coolant outlet and its level in the casing.

 In FIG. 1 shows the proposed heat exchanger in longitudinal section; in FIG. 2 is a cross section AA in FIG. 1; in FIG. 3 is a schematic diagram of a strapping of a mobile heat exchanger in the well.

 The heat exchanger consists of a casing 1 with a cover 2. In the casing 1 in the form of an S-shaped tube bundle are pipe pairs consisting of outer pipes 3 and inner pipes 4 concentrically located in them with outer spiral ribs 5. The annular spaces of the pipe pairs are connected in series with each other arched jumpers 6. The inner pipes 4 are connected in series with each other using U-shaped tubes 7. The first pipe pair is continued, where behind the cover 2 the outer pipe 3 is provided with a discharge channel 8, and the inner pipe 4 under a driving channel 9 for entering the coolant (steam). The inner pipe 4 in the last lower pipe pair has a tangential exit 10 into the inner cavity of the casing 1, which is equipped with an L-shaped outlet pipe 11 with a side hole 12 for free exit of the heat carrier (steam condensate) into the atmosphere and a drain pipe 13. The last outer pipe 3 also behind the cover 2 has a continuation and is equipped with a supply channel 14 for the entry of the heated fluid into the heat exchanger.

 The proposed heat exchanger mounted on the chassis of a two-wheeled trailer is used to transfer heat from steam to hydrocarbon solvents (hydrodistillates) while simultaneously using the thermal and chemical (combined) method for cleaning paraffin deposits from the surface of well equipment. Depending on the well flushing technology, the heated solvent is pumped into the annulus or into the tubing string (tubing), or through smaller diameter flushing tubes deflated into the tubing.

 Moreover, in addition to the mobile heat exchanger 15, the pumping unit (CA-320) 17, the mobile steam unit (PPU) 18 and the tank truck 19 with the technological liquid-solvent are used for the technology, which are connected to the well 16 according to the technological scheme shown in FIG. 3.

 The heat exchanger operates as follows.

 Water vapor (coolant) from the PUF 18 is fed into the supply channel 9 of the inner pipe 4. The coolant, passing through the inner pipes 4 and through the tangential outlet 10 in the form of steam condensate with a sufficiently high temperature, enters the casing 1. As the level of condensate increases, air from the casing 1 is displaced through the side holes 12 of the L-shaped pipe 11.

 After the condensate reaches the level covering the four lower pipe pairs, it is poured out through the L-shaped outlet pipe 11. In this case, the accumulated steam condensate with a steady level in the casing 1 provides external heating of the outer pipes 3 and at the same time performs the function of a hydraulic shutter preventing the passage of non-condensed steam. The latter occupies a space above the condensate level.

 The tangential exit 10 determines the rotation of the condensate by the exit stream and a uniform temperature distribution over the cross section of the casing 1.

 The heated liquid — a hydrocarbon solvent — is pumped into the annulus through the inlet channel 14 of the outer pipe 3. Using the pump unit 17, the movement of the “cold” solvent and water vapor occurs according to the countercurrent flow pattern and due to heat exchange of the inner and outer sides of the annular space between the inner 4 and outer With 3 pipes, the hydrocarbon solvent is heated to the desired temperature.

 Spiral ribs 5, designed to increase the surface area of heat transfer, also provide a circular rotation of the heated fluid around the "hot" pipe and mixing gaseous fractions released from the hydrocarbon solvent during heating.

 The heated hydrocarbon solvent is pumped through the discharge channel 8 through the connecting line into the well 16. Upon termination of the heat exchange process, due to the S-shaped arrangement of the series-connected pipe pairs, steam condensate flows from the internal pipes 4 into the casing 1 and through the drain valve 13 to the outside. This allows you to reliably operate a mobile heat exchanger in the treated wells at a negative ambient temperature.

 The temperature of the coolant in the inlet channel 9 and the heated fluid in the outlet channel 8 is controlled by a thermometer installed in a heat chamber (not shown in the drawing).

 The required temperature of the solvent at the outlet of the heat exchanger is achieved either by controlling the temperature of the steam or its flow rate generated by the PUF, or at constant values of these parameters by changing the flow rate of the solvent using the pump unit.

The table below shows the thermodynamic mode of operation of a mobile heat exchanger. With a constant value of the parameters (G = 1600 kg / h, T _inlet = 108 ^o C), the steam gives the obtained temperature values of the heated liquid (solvent) at the outlet of the heat exchanger depending on the ambient temperature.

 The obtained values of the temperature of the solvent at the outlet of the heat exchanger satisfy the requirements for the technology of thermochemical processing in different periods of the seasons. The proposed mobile heat exchanger is used in pilot industrial implementation of well treatment technology, and tests have shown its high efficiency and reliability when heating process fluids.

Sources of information:
1. Ivanets K.Ya., Leibo A.N. Equipment for oil refineries and its operation. M., Chemistry, 1966, p. 152.

 2. SU 397737, 1973.

Claims (1)

 A heat exchanger for heating process fluids in a well, comprising inlet and outlet channels for a coolant and a heated fluid, series-connected multi-way pipe pairs consisting of external pipes and internal pipes concentrically placed in them with spiral finning of external surfaces, characterized in that it is mobile, pipe pairs are arranged in the form of an S-shaped horizontal tube bundle and are placed in a cylindrical casing, the lower last inner pipe having gentsialny out into the inner cavity of the cylindrical casing, which is provided with L-shaped transfer tube with a lateral opening at the top, providing a coolant outlet and its level in the housing.

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