Abstract: A flameless nitrogen vaporizing unit includes a first internal combustion engine driving a nitrogen pump through a transmission. A second internal combustion engine drives three hydraulic oil pumps against a variable back pressure so that a variable load may be imposed upon the second engine. Liquid nitrogen is pumped from the nitrogen pump driven by the first engine into a first heat exchanger where heat is transferred from exhaust gases from the first and second internal combustion engines to the liquid nitrogen to cause the nitrogen to be transformed into a gaseous state. The gaseous nitrogen then flows into a second heat exchanger where it is superheated by an engine coolant fluid to heat the gaseous nitrogen to essentially an ambient temperature. The superheated nitrogen is then injected into the well. The engine coolant fluid flows in a coolant circulation system. Heat is transferred to the coolant fluid directly from the internal combustion engine.

Abstract: A flameless nitrogen vaporizing unit includes a first internal combustion engine driving a nitrogen pump through a transmission. A second internal combustion engine drives three coolant circulation pumps against a variable back pressure so that a variable load may be imposed upon the second engine. Liquid nitrogen is pumped from the nitrogen pump driven by the first engine into a first heat exchanger where heat is transferred from exhaust gases from the first and second internal combustion engines to the liquid nitrogen to cause the nitrogen to be transformed into a gaseous state. The gaseous nitrogen then flows into a second heat exchanger where it is superheated by an engine coolant fluid to heat the gaseous nitrogen to essentially an ambient temperature. The superheated nitrogen is then injected into the well. The engine coolant fluid is circulated in a coolant circulation system by the coolant circulation pumps. Methods of vaporizing nitrogen are also disclosed.

Abstract: A flameless nitrogen vaporizing unit includes a first internal combustion engine driving a nitrogen pump through a transmission. A second internal combustion engine drives three hydraulic oil pumps against a variable back pressure so that a variable load may be imposed upon the second engine. Liquid nitrogen is pumped from the nitrogen pump driven by the first engine into a first heat exchanger where heat is transferred from exhaust gases from the first and second internal combustion engines to the liquid nitrogen to cause the nitrogen to be transformed into a gaseous state. The gaseous nitrogen than flows into a second heat exchanger where it is superheated by an engine coolant fluid to heat the gaseous nitrogen to essentially an ambient temperature. The superheated nitrogen is then injected into the well. The engine coolant fluid flows in a coolant circulation system. Heat is transferred to the coolant fluid directly from the internal combustion engine.

Abstract: A flameless nitrogen vaporizing unit includes a first internal combustion engine driving a nitrogen pump through a transmission. Connected to the transmission is a transmission retarder for varying the load on the first internal combustion engine by varying a level of hydraulic fluid present in the transmission retarder. A second internal combustion engine drives three hydraulic oil pumps against a variable back pressure so that a variable load may be imposed upon the second engine. Liquid nitrogen is pumped from the nitrogen pump driven by the first engine into a first heat exchanger where heat is transferred from exhaust gases from the first and second internal combustion engines to the liquid nitrogen to cause the nitrogen to be transformed into a gaseous state. The gaseous nitrogen then flows into a second heat exchanger where it is superheated by an engine coolant fluid to heat the gaseous nitrogen to essentially an ambient temperature. The superheated nitrogen is then injected into the well.

Abstract: A fluid flow measuring device comprising a hollow cylindrical housing having a plurality of recessed areas extending about a portion of the interior surface of the housing and through only a portion of the thickness of the housing; fluid flow straightening means; means for measuring the flow of fluid through the housing; retaining means having a portion inserted in the recessed area in said hollow housing and having portions substantially conforming to a portion of the exterior surface of said fluid flow straightening means; and fastening means securing said retaining means to said fluid flow straightening means whereby both longitudinal and rotational movement of said fluid flow straightening means in said hollow housing is prevented by said retaining means engaging said hollow housing and substantially conforming to a portion of the exterior surface of said fluid flow straightening means when said retaining means is secured to said fluid flow straightening means by said fastening means.

Abstract: A fluid flow measuring device comprising a hollow cylindrical housing having a plurality of recessed areas extending about a portion of the interior surface of the housing and through only a portion of the thickness of the housing; fluid flow straightening means having a plurality of recessed areas in the exterior surface of the fluid flow straightening means; a plurality of fastening means, each fastening means having a portion inserted in the area formed when a recessed area in the housing and a recessed area in the fluid flow straightening means are aligned while the remaining portion of the fastening means substantially conforms to the exterior surface of the fluid flow straightening means thereby fastening the fluid flow straightening means to the housing; and means for measuring the flow of fluid through the housing. Alternately, the housing may have a continuous recess about the interior surface in place of the plurality of recessed areas.