Automatic flow control in mixing fracturing gel

1. A system for mixing fracturing gel, the system comprising:

a dry gel mixing chamber comprising a bladed impeller carried to rotate in the mixing chamber;

a dry gel inlet in fluid communication with the mixing chamber, the dry gel inlet directly connected to a tank containing dry, non-hydrated, particulate material, such that, when particulate material is dispensed from the tank, the dispensed particulate material is provided to the dry gel inlet in a non-hydrated state and introduced to the mixing chamber for contact by the bladed impeller;

a hydrating fluid inlet in fluid communication with the mixing chamber;

a hydrating fluid source pump fluidly coupled to the hydrating fluid inlet to circulate a hydrating fluid through the dry gel mixing chamber as the bladed impeller rotates, the pump configured to operate at multiple different values of a flow condition to the hydrating fluid inlet;

a valve fluidly coupled to the hydrating fluid inlet and coupled to a controller that senses a flow condition of the valve and is configured to automatically adjust a flow area through the valve in response to a change in an operating flow condition of the pump so that, as the hydrating fluid source pump operates at the multiple different values of the flow condition to the hydrating fluid inlet, the valve maintains a constant specified flow condition of hydrating fluid into the mixing chamber; and

a mixed gel outlet oriented outward from the mixing chamber, and leading to a fluid conduit extending to a hydration tank.

2. The system of claim 1 , where the specified flow condition is flow rate.

3. The system of claim 1 , where the specified flow condition is pressure.

4. The system of claim 1 , where the valve comprises a pressure responsive valve adapted to control the flow of hydrating fluid into the mixing chamber automatically in response to a pressure difference between the hydrating fluid flow upstream and downstream of the valve.

5. The system of claim 3 , where the valve comprises:

a valve closure moveable to adjust the flow through the valve;

a diaphragm coupled to move the valve closure;

a regulator coupled to the flow upstream of the valve closure, the flow downstream of the valve closure and to a control volume adjacent the diaphragm, the regulator configured to feed pressure to the control volume that extends the diaphragm to move the valve closure toward closed when the pressure upstream of the valve closure exceeds the specified pressure.

6. The system of claim 5 , further comprising a control fluid enclosed within the control volume, the control fluid comprising a different fluid than the hydrating fluid.

7. The system of claim 1 , where the valve comprises:

a valve closure moveable to adjust the flow through the valve;

a sensor downstream of the valve closure; and

a controller coupled to the sensor and configured to move the valve closure in response to an output of the sensor.

8. The system of claim 1 , where each of the multiple different values of the flow condition comprises a unique inlet pressure at the hydrating fluid inlet that is produced by operation of the hydrating fluid source pump.

9. The system of claim 1 , where the valve comprises a butterfly type closure.

10. A device for mixing dry fracturing gel with hydrating fluid, comprising:

a mixer defining an interior mixing chamber;

a dry gel inlet in fluid communication with the interior mixing chamber, the dry gel inlet directly connected to a tank containing dry, non-hydrated, particulate material, such that, when particulate material is dispensed from the tank, the dispensed particulate material is provided to the dry gel inlet in a non-hydrated state and introduced to the mixing chamber;

a hydrating fluid inlet in fluid communication with the interior mixing chamber;

a hydrating fluid source pump fluidly coupled to the hydrating fluid inlet and configured to circulate a hydrating fluid through the interior mixing chamber-at multiple different operating pressures;

an automatic pressure reducing valve coupled to the hydrating fluid inlet and coupled to a controller that senses a flow condition of the valve and is configured to automatically adjust a flow area through the valve in response to a change in the operation of the pump so that, as the hydrating fluid source pump operates at the multiple different operating pressures, the valve maintains a constant specified pressure of the hydrating fluid supplied into the interior mixing chamber; and

a mixed gel outlet oriented outward from the mixing chamber, and leading to a fluid conduit extending to a hydration tank.

11. The device of claim 10 , where the valve comprises a butterfly type valve closure.