JPS5846679B2 - Geothermal steam turbine power station and its operation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A geothermal steam turbine cycle is described that can operate effectively with geothermal steam contaminated with high concentrations of non-condensable gases.

The contaminated steam is used to evaporate clean gas-free turbine condensate, which is then fed back to the condenser steam turbine.

In a conventional geothermal steam turbine cycle, 1
Alternatively, steam is produced by flash evaporation in two stages and the separated steam is used in a one- or two-inlet steam turbine.

If the concentration of the source non-condensable gas is high, the mechanical work required to remove it from the condenser can be prohibitively large.

One solution to this problem is to use contaminated steam to evaporate the organic fluid in a closed Rankine cycle.

Gas escapes from the heat exchanger under pressure and there is relatively little degradation in cycle performance.

The above is described in detail in US Pat. No. 3,862,545 and US Pat. No. 3,845,627.

US Pat. No. 3,862,545 describes the removal of non-condensable gases from the condenser of a turbine via piping 14 shown in the drawings.

This gas may be hydrogen sulfide or carbon dioxide.

An example of a closed Rankine cycle is U.S. Pat. No. 384,562.
It is shown in Figure 4 of No. 7.

As previously mentioned, removing non-condensable gases from the turbine condenser can require significant power consumption in terms of pump energy, which can have a negative impact on cycle performance. It may be harmful.

For geothermal applications, closed Rankine cycle does not use steam turbine technology.

This is because organic compounds make the best working fluids.

US Pat. No. 3,782,468 describes the separation of geothermal fluids into hot liquids and contaminated vapors.

The contaminated steam is further processed to liberate CO2, which is reinjected into the geothermal well to help elevate the geothermal fluids without forming harmful ore deposits.

The hot liquid is used to drive a turbine through clean steam.

No. 3,953,972, condensate (distilled water) and a geothermal fluid are passed through a non-contact heat exchange to heat the condensate and generate steam for a steam turbine.

At this time, the liquid geothermal fluid is flash-evaporated in an evaporator to remove non-condensable gases.

U.S. Pat. No. 4,026,111 describes a method for removing non-condensable gases from a turbine power fluid by pre-flash vaporizing a geothermal liquid and using the remaining liquid phase to generate clean steam. has been done.

The last two U.S. patents listed are U.S. Patent No. 39539.
No. 72 is of interest in that it does not directly use geothermal fluid to generate the power fluid that drives the turbine.

In this sense, this US patent is almost a binary cycle since condensate is the only fluid used to drive the turbine.

In US Pat. No. 4,026,111, the opposite is true.

That is, the only power fluid is uncontaminated geothermal fluid.

The solution described here uses dirty steam to evaporate clean condensate from the turbine.

Again, the gas escapes from the heat exchanger under pressure, but there is relatively little deterioration in cycle performance.

However, what is really important is the use of an ordinary steam turbine for this cycle.

The invention is for a steam turbine that utilizes geothermal fluid to create one clean source of steam to the steam turbine and utilizes heated condensate to create another clean steam source to the turbine. improves on prior art by providing a geothermal cycle of

The other source is created by exchanging contaminated steam with condensate.

It is an object of this invention to provide an improved geothermal steam turbine cycle.

Next, preferred embodiments of the invention will be described with reference to the drawings.

The drawing shows a geothermal steam turbine cycle of the invention.

A geothermal resource, ie a generation well 1 , supplies high temperature liquid vapor to a primary liquid-gas separator (flash evaporator) 3 via a pipe 2 .

Although this invention can use any geothermal resource,
It is particularly advantageous when the geothermal resource contains non-condensable gases.

The purpose of separating liquid and gas is to retain the brine while releasing non-condensable gases from the brine as contaminated vapors.

For this purpose, brine from geothermal resources is separated into a high-temperature liquid phase and a high-temperature gas phase containing contaminated steam by primary flash evaporation.

The purpose of the geothermal cycle is to generate usable power from geothermal resources.

Using steam turbine 4, steam energy is transferred to load 6
The purpose of this is to convert the mechanical output of the shaft 5 into a mechanical output that can be used to drive the motor.

This load may be, for example, a generator. A turbine receives steam into a high pressure section 7 and a downstream low pressure section 8 and discharges the steam through an exhaust end 9 to a condenser 10 .

This figure shows a bidirectional flow steam turbine as an example of a prime mover.

However, it will be appreciated that other forms of steam turbines may be used without departing from the scope of the invention.

Condensate is pumped by pump 11 and is used to generate steam as shown.

A portion of the pump condensate can be used in the cooling tower 12.

On the other hand, a portion of the cooling tower liquid is used in the condenser 10.

Excess liquid in the cooling tower is transferred via piping 13 to reinjection well 14
sent to.

The primary liquid and gas separation in the flash evaporation tank 3 produces a liquid phase portion (brine) 15 and a vapor portion 16 contaminated with the gas phase.

This contaminated vapor consists of steam and non-condensable gases.

The liquid phase 15 is sent to a flash evaporation tank 17 where it is evaporated by secondary flash evaporation and steam header 18
generates uncontaminated steam against

Liquid that has not been flashed is discharged via conduit 19.

Brine entering conduit 19 can be combined with cooling tower liquid 13 and reinjected into aquifer 14.

Alternatively, depending on site conditions, the brine in conduit 19 can be flash evaporated once more to generate more steam.

Uncontaminated steam in line 18 is introduced into low pressure turbine section 8 .

Contaminated steam in pipe 16 is introduced into counterflow heat-and-moisture exchanger 20 .

The condensate taken out from the condenser 10 is pumped to the opposite end of the heat exchanger 20.

Heat transfer takes place between the condensate and the contaminated steam, and the uncontaminated steam is output from the heat exchanger to the pipe 21 and becomes high pressure steam for the high pressure section 7 of the turbine 4.

The contaminated vapor exits the heat exchanger 20 as a liquid, at which point the non-condensable gas can be vented into line 22 and the remaining condensate can be returned to the condenser 10 via line 23.

Table 1 shows the resource conditions and steam power plant conditions as the expected performance of the geothermal steam turbine cycle.

The advantages of the cycle described above are as follows.

Unlike the prior art mentioned at the beginning of the specification, the degree of primary flash evaporation does not affect the cycle.
Does not require well pump operation.

This is because, downstream of the primary flash evaporation, there is a heat exchanger for steam generation that utilizes the heat of the released steam, although it is contaminated.

The turbine uses two sources of clean steam.

That is, the steam obtained by flash evaporation from the flash evaporation tank 17 and the high pressure steam from the heat exchanger 20.

No pumping is required to separate the non-condensable gas, which can be stripped after the contaminated vapors have been condensed in the heat exchanger 20.

[Brief explanation of drawings]

The figure is a schematic diagram illustrating the geothermal steam turbine cycle of the present invention. Explanation of main symbols, 3.17: Flash evaporator, 4: Steam turbine, 10: Condenser, 20: Heat exchanger.

Claims (1)

[Scope of Claims] 1. A geothermal steam turbine power station for converting high temperature geothermal brine contaminated with non-condensable gases into usable power output, including at least one steam turbine and a geothermal brine contaminated with high temperature liquids. first steam generating means for receiving the hot liquid portion and producing a first uncontaminated low pressure steam input to the steam turbine; and means for receiving the contaminated steam portion; a second steam generation means for indirectly exchanging heat of said steam portion with turbine feed water to produce a second uncontaminated high pressure steam input to said steam turbine. 2. In the geothermal steam turbine power plant according to claim 1, the first steam generation means receives the high temperature liquid portion and supplies the uncontaminated low pressure first steam input to the steam turbine. said second steam generating means receives said contaminated gas portion for heat exchange with condensate of said steam turbine and generates said uncontaminated high pressure second steam to said steam turbine. A geothermal steam turbine power station containing a non-contact counterflow heat exchanger that produces input. 3. In the geothermal steam turbine power plant according to claim 1, the separation means is constituted by a first flash evaporation section that separates the high temperature geothermal brine into a high temperature liquid part and a contaminated gas part, and the low pressure a first steam generating means of comprises a second flash evaporator receiving said hot liquid portion to produce a first uncontaminated steam input to said steam turbine; , a non-contact counterflow moist heat exchanger connected to the first flash evaporator and receiving the contaminated gas portion, the heat exchanger being connected to the condensate feedwater of the turbine to remove the condensate feedwater from the a geothermal steam turbine power plant for exchanging heat with a gas portion to produce the uncontaminated, high pressure second steam input to the steam turbine; 4. In a method of operating a geothermal steam power plant for converting high temperature geothermal brine contaminated with non-condensable gases into usable power output, the geothermal brine is separated into a hot liquid portion and a contaminated steam portion, and the The hot liquid portion is flash-evaporated to provide a first, uncontaminated, low-pressure power steam to the steam turbine, and the contaminated steam is subjected to non-contact, indirect, heat-and-moisture exchange with the turbine condensate to form the steam. A method comprising the steps of providing a second, uncontaminated, high pressure power steam to a turbine and operating the steam turbine with the first and second power steam.